An ecosystem approach to fishery management addresses human activities and environmental factors that affect an ecosystem, the response of the ecosystem, and the outcomes in terms of benefits and impacts on humans. The essence of the framework is characterized by stresses, responses, and benefits. The traditional view of a fishery narrowly fits into this framework with fishing as the only stress, the ecosystem response specified solely in terms of the effect of fishing mortality on a single species, and the outcome in terms of catch. One way of achieving an ecosystem approach is to incrementally add to the list of stresses, the scope of the ecosystem responses, and the type of benefits considered in fishery management.
Additional stressors might be forms of degradation in habitat and environmental quality. Experiments on the biological response of the resource (the exploited species) to these stresses would allow the stresses to be taken into account in population models that are traditionally used to determine the effect of fishing. In this way, several different forms of population stress can be compared quantitatively to the stress of fishing. The comparison would be helpful because much is known about how populations respond to fishing but less about population responses to other forms of stress. Even if managers decide not to experiment by deliberately stressing fisheries, they can instead take advantage of whole-system "experiments" (e.g., wars, major environmental fluctuations) and other management actions as described in the section on adaptive management above.
The type of responses to stresses can also be expanded incrementally by trophically linking species. Multispecies virtual-population analysis is an example of this approach. Ultimately, exploited species need to be linked to other components of ecosystems so that indirect responses to stress can be addressed.
Finally, there is a need for incrementally increasing the scope of benefits from fisheries. Benefits of recreational and subsistence fisheries need to be determined. Nonmonetary benefits of ecosystem services also need to be considered. Methods that express benefits in a common metric need to be applied and improved so that decisions can be made between alternative forms of management of fisheries and other human activities.
This incremental approach will take a long time to evolve to a point where it takes account of all the important stresses, responses, and benefits, but it allows immediate progress by taking advantage of the existing framework that is used in fisheries.
Ecosystem Monitoring. An ecosystem approach to fishery management requires a long-term commitment to systematic and carefully standardized observations